Bone plates for internal fixation of fractured bones should generally conform to the contours of the fractured bone surface. This is especially true for compression plates that are screwed tightly against the bone. Matching the plate shape to the bone contours is important with compression plates in order to allow proper distribution of loads between the bone and the plate during healing of the fracture. It is also desirable for the plate to have a low profile and to blend with the bone surface as much as possible so as not to irritate or interfere with surrounding soft tissues, nerves, tendons, vessels, etc.
One type of bone plate for acetabular and other pelvic fractures is called a reconstruction bar. Conventional reconstruction bars are generally formed from a biocompatible metal that may be bent by the surgeon using special tools in order to configure the bar to conform to the bone. Typically the surgeon first forms a thin metal template by hand to conform to the bone surface at the fracture site. Working through an open incision, the surgeon bends the template to approximate the desired shape, places the template against the bone surface, removes the template, adjusts the shape of the template and repeats these steps until the template closely matches the shape of the bone surface. Then the surgeon, sometimes with the help of an assistant, uses a number of special forming tools to bend the reconstruction bar to be implanted into approximately the same configuration as the template, visually holding the bar and template side-by-side to assess when the bar is adequately similar to the template. This procedure may take several minutes of time and a significant amount of skill. The bar may then be attached to the bone using conventional cortical screws. It is not likely that the bar shape exactly matches the bone surface shape, so tightening of the bone screws may draw the bar against the bone surface, thereby inducing bending preloads at various locations along the bar due to the spring-back characteristic of the bar material. Alternatively, the bar may be implanted with significant gaps between various locations of the bar and the bone surface, resulting in the uneven transfer of loads between the bone and bar construct. Therefore, it would be advantageous to provide a reconstruction bar that may be implanted more quickly by the surgeon, requires fewer ancillary tools, is more conformable and contoured to the bone surface and is at least as effective as a fixation device compared to conventional reconstruction bars.
Another issue currently faced by orthopedic device manufacturers is the need to provide a full line of bone plates for a large variety of bone fractures and patient anatomies. The manufacturing costs associated with forming each rigid, one-piece bone plate is significant due largely to the need to configure the plate to approximately match the bone surface shape. Furthermore, a large product inventory must be provided to the user (hospitals) to be prepared for the many types of fractures and patient anatomies to be treated. Accordingly, it would be advantageous to provide bone plates that have broader indications, where each plate may be suitable for a larger variety of fractures and patient anatomies than currently available plates. Potentially, such bone plates may be produced at lower costs than current plates and inventories reduced without compromising surgical outcomes.
What is also needed is a bone fixation device and method such as described above (may be implanted quickly, requires fewer ancillary tools, is at least as effective as a fixation device compared to conventional fixation devices) that may be configured to conform to a broad, contoured bone surface. The fixation device may, for example, reduce the need to use multiple bone plates for particular types of fractures, including comminuted acetabular fractures (see Chapter 20 of Orthopaedic Surgery Essentials: TRAUMA, published by Lippincott Williams and Wilkins, 2006).
There is also a need to provide surgeons with devices and methods to create custom, bone fixation devices intraoperatively for less common types of bone fractures, and generally to provide recourse in cases in which conventional bone plates are unavailable.